This invention relates to electrical switches, and in particular to switches of the contactless type wherein the switching function is performed by a solid state semiconductor element.
The performance of conventional electrical switch contacts is subject to degradation caused by a number of factors. In particular contact wear can arise from mechanical wiping of the contacts and from arcing between the contacts during operation of the switch. Contaminant materials can form deposited coatings on the contact surfaces causing unacceptably high resistance. Furthermore, unless precautions are taken, contact bounce can occur on closing the switch giving rise to electrical noise. This problem renders conventional switches inappropriate for use in conjunction with integrated circuits where a significant mismatch in lifetime and reliability are apparent. The object of the present invention is to minimise or to overcome these disadvantages.